Malaria overtreatment a 'risk to public health in Asia'

[PESHAWAR] Overdiagnosis and mistreatment of malaria in central and south Asia may be widespread, leading to the neglect of other serious illnesses, according to a new study from Afghanistan.

The findings contradict a common assumption that there is a greater risk of malaria being missed than overdiagnosed in this region of low malaria prevalence, compared with Africa or South-East Asia.

Because malaria in this region is rare and mainly caused by a less dangerous form of the disease — Plasmodium vivax — overtreatment may actually be worse for public health than it is in Africa or South-East Asia, says a study published in the British Medical Journal last month (24 July).

Researchers assessed the accuracy of malaria diagnoses and treatment for over 2,300 patients with suspected malaria at 22 clinics in northern and eastern Afghanistan. Some of the clinics relied upon clinical evidence of the disease, while others used diagnostic procedure carried out by microscopy.

They then tested the blood samples of the patients independently using microscopy.

The researchers found that a large proportion of patients with negative microscopy slides were still being prescribed antimalarial treatment. This meant that the real causes of these diseases went untreated.

Compared to clinics with no microscopy equipment — where around 99 per cent of people with negative tests for malaria (run by the researchers) received treatment — the clinic with microscopy technology improved the targeting of treatment, but only by around 50 per cent.

The problems stem from clinicians ignoring negative malaria test results and from tests showing 'false positives', tests showing as positive for malaria, when in fact the patient does not have the disease.

Experts in Pakistan say the findings are likely to reflect the situation across South Asia.

"The problem is complex. About 80 per cent of patients in rural areas are being treated by unqualified doctors," said Adnan Ali Shah, a public health specialist at the Khyber Pakhtunkhwa province's health department.

"In 2005, we collected patient data from 18 hospitals in rural areas of Pakistan," Shah said. "The findings were extremely discouraging, as of the 1,344 patients showing malaria symptoms, only 398 had been subjected to blood tests for malarial parasites."

Despite this, he added, "1,210 patients had been given antimalarial drugs".

The patients "are in the habit of resorting to self-medication", which could also affect diagnoses, Shah added.

Imtiaz Iqbal, a WHO researcher based in Islamabad, Pakistan, told SciDev.Net that malaria overdiagnosis and mistreatment in rural Pakistan are causing complications that often go unnoticed.

The high cost of treatment by consultant physicians also leads to people self-diagnosing or visiting substandard clinics, Iqbal said.